Supported olefin polymerization catalysts

ABSTRACT

Supported heterometallocene catalysts wherein the support is a particulate polymeric material are provided. The catalysts have a transition metal complex containing at least one anionic, polymerization stable heteroatomic ligand associated with the transition metal and a boron activator compound deposited on the support. Polymeric supports used for the heterometallocene catalysts of the invention are homopolymers of ethylene and copolymers of ethylene and C 3-8  α-olefins.

This is a division of application Ser. No. 09/433,711, filed Nov. 19,199, now U.S. Pat. No. 6,281,155.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to polymer supported transition metal catalystsuseful for the polymerization of olefins. More specifically, thecatalysts are supported heterometallocenes and comprise a transitionmetal coordination complex having at least one anionic,polymerization-stable heteroatomic ligand and a boron compound activatoron a particulate polymer support. The polymeric supports are ethylenehomopolymers and copolymers of ethylene and C₃₋₈ α-olefins.

2. Description of the Prior Art

The ability of metallocene catalysts to produce polyolefin resins ofnarrow molecular weight distribution (MWD), low extractables and uniformcomonomer incorporation has spurred activity with these and othersingle-site catalyst systems. As used herein, single-site catalystsrefer to transition-metal catalysts having one or morepolymerization-stable cyclopentadienyl (Cp) ligands, Cp derivativeligands, heteroaromatic ligands or constrain-inducing ligands associatedwith the transition metal and which, when used to polymerize α-olefins,produce resins having the characteristic narrow MWD (M_(w)/M_(n)).

While single-site catalysts have been incorporated on supports for usein gas phase, slurry and related processes, reactor fouling and/orsheeting and reduced activity are problems. Fouling results in poor heattransfer, poor polymer morphology and, in extreme circumstances, canforce reactor shutdown. Numerous procedures have been proposed to reducereactor fouling and sheeting. For example, electrical methods have beenproposed to control static electricity and antistatic agents have beenincluded in the polymerization for this purpose. Surface treatments ofthe interior walls of polymerization vessels have also been employed.Various other techniques, such as the use of surface modifiers for thesupport material used, have also been utilized during catalystpreparation.

New supported single-site catalyst systems capable of reducing polymerstickiness and eliminating or minimizing reactor fouling are constantlybeing sought particularly, if the catalysts are derived from readilyavailable and economical materials and if catalyst is not adverselyaffected. These and other objectives are achieved with the supportedcatalysts of the invention wherein a heterometallocene catalyst andboron compound are supported on a particulate polyethylene resin.

The use of polymer supports with Ziegler-Natta catalysts is known. Forexample, in U.S. Pat. No. 3,925,338 Ziegler-Natta catalysts aredeposited on different particle size polyethylene supports to controlthe particle size in gas phase polymerizations. The use of vanadiumcatalysts supported on various speroidal high molecular weight polymersis disclosed in U.S. Pat. No. 4,098,979. Hoff, in U.S. Pat. Nos.4,268,418 and 4,404,343 discloses the use of polymeric carriers,preferably containing a small amount of polar groups, as catalystsupport. Carboxyl group-containing polymers modified with magnesium areused to support polymerization catalysts in U.S. Pat. No. 5,409,875.

Polymeric supports have been used as a means of attaching metallocenecatalysts to the support. In U.S. Pat. No. 5,492,985, a polymer boundcyclopentadienyl ligand is reacted with a metallated polystyrene toobtain a polymer bound metallocene catalyst useful for olefinpolymerizations. In a similar approach, metallocene catalysts tetheredto a copolymer support, are disclosed in U.S. Pat. No. 5,587,439. U.S.Pat. No. 4,921,825 discloses a process for forming a solid catalyst byreacting a metallocene, such as bis(cyclopentadienyl)zirconiumdichloride, with an aluminoxane in the presence of a particulate organicor inorganic carrier. Similarly, the reaction product of a metallocenewith an aluminoxane or a microporous polymeric support is disclosed inEP 563917-A1. In all of the foregoing, the metallocene is either reactedwith the support via functionality present on the support material orthe metallocene compound is reacted with an aluminoxane. Moreover, noneof the references disclose the use of heterometallocenes.

SUMMARY OF THE INVENTION

The invention relates to supported heterometallocene catalystscomprising a particulate ethylene homopolymer or ethylene-C₃₋₈ α-olefincopolymer support, a transition metal coordination complex containing atleast one anionic, polymerizationstable heteroatomic ligand and a boronactivator compound. More specifically, the catalysts of the inventionwhich are useful for the homopolymerization and copolymerization ofolefins utilize a transition metal compound of the formula

(L*)_(n)(L)_(m)M(X)_(y)

wherein M is a Group 3-10 metal, L* is an anionic, polymerization-stableheteroatomic ligand, L is a carbocylic or constrain-inducing ligand orL*, X is hydrogen, halogen, hydrocarbyl, alkoxy, siloxy or dialkylamido,n is 1 to 4, m is 0 to 3, y is 1 to 4 and n+m+y is equal to the valenceof the transition metal M and a boron activator compound.Tripentafluorophenyl N,N-dimethylanilinium tetra(pentafluorophenyl)borate and trityl tetrakis(pentafluorophenyl)borate are particularlyuseful boron activators. Homopolymers and copolymers of ethylene areuseful support materials particularly wherein the particles arespheroidal or substantially spheroidal. The polymer supports have meltindexes from 0.1 to 400 g/10 min and median particle sizes from 0.5 to1000 microns. A process for polymerizing α-olefins using the catalystsof the invention is also described.

DETAILED DESCRIPTION OF THE INVENTION

Catalysts of the invention are supported heterometallocenes and comprisea transition metal coordination complex having at least one anionic,polymerization-stable heteroatomic ligand, a boron compound activatorand a particulate polymeric support. Polymeric supports of the inventionare polyethylene homopolymers and copolymers.

The term heterometallocene as used herein refers to single-sitecatalysts having at least one anionic, polymerization-stableheteroatomic ligand associated with the transition metal.Polymerization-stable ligands are those which remain associated with thetransition metal under polymerization conditions. The transition metalcomplex may also contain other anionic, polymerization-stable ligands,such as Cp or Cp derivative ligands, constrain-inducing ligands as wellas other groups such as hydrocarbyl, halogen and the like.

Transition-metal coordination complexes used for the preparation of thesupported heterometallocene catalysts of the invention correspond to theformula:

(L*)_(n)(L)_(m)M(X)_(y)

wherein M is a Group 3-10 metal, L* is an anionic, polymerization-stableheteroatomic ligand, L is a carbocylic or constrain-inducing ligand orL*, X is hydrogen, halogen, hydrocarbyl, alkoxy, siloxy or dialkylamido,n is 1 to 4, m is 0 to 3, y is 1 to 4 and n+m+y is equal to the valenceof the transition metal M. Preferably, the transition metal will be aGroup 4, 5 or 6 metal and it is especially useful when the metal is aGroup 4 metal, particularly, titanium, zirconium or hafnium. X ispreferably halogen or hydrocarbyl. L is preferably another heteroatomicligand, which can be the same or different, Cp or a Cp derivative.

It is particularly advantageous when L* is a heteroaromatic ligandselected from the group consisting of substituted and unsubstitutedboraaryl, pyrrolyl, azaborolinyl, quinolinyl and pyridinyl ligands. Suchheteroaromatic ligands are described in U.S. Pat. Nos. 5,554,775,5,539,124, 5,637,660 and PCT International Application WO 96/34021, theteachings of which are incorporated herein by reference. Theaforementioned heterocyclic ring systems may be part of a larger fusedring structure.

Carbocyclic ligands from which L is selected include substituted andunsubstituted Cp and Cp derivative ligands wherein the Cp ring is partof a fused ring structure, such as indenyl, 2-methylindenyl,tetrahydroindenyl, fluorenyl and the like. Polymerization-stable anionicligands of this type are described in U.S. Pat. Nos. 4,791,180 and4,752,597 which are incorporated herein by reference. Additionally, Lcan be a constrain-inducing ligand such as described in U.S. Pat. No.5,272,536 which is incorporated herein by reference.

The L* and L ligands can be bridged. Bridging can be between the same ordifferent ligand types. For example, a Cp ligand may be bridged toanother Cp or to a heteroatomic ligand, such as a boraaryl moiety,through a bivalent bridging group such as an alkylene, phenylene, silyl,phosphorus-containing groups, boron-containing groups andoxygen-containing groups. Exemplary groups within the above classes ofbridging moieties are methylene, ethylene, phenylene, dialkylsilyl,diarylalkyl or their substituted versions and the like. By bridging itis possible to change the geometry around the transition metal andthereby modify catalyst activity, comonomer incorporation and polymerproperties.

In one highly useful embodiment of the invention, the transition metalcomplex is a complex of titanium, zirconium or hafnium, L* is selectedfrom the group consisting of substituted and unsubstituted boraaryl,pyrrolyl, azaborolinyl, quinolinyl and pyridinyl ligands, n is 1 or 2, mis 0 or 1, L is an alkyl substituted or unsubstituted Cp or Cpderivative and X is selected from the group consisting of bromine,chlorine, C₁₋₄ alkyl, phenyl, alkyl substituted phenyl, benzyl or alkylsubstituted benzyl.

A boron activator compound is employed with the transition metal complexto form the polymer supported catalysts of the invention. Knownactivator compounds capable of converting, i.e., ionizing, thetransition metal complex to the active cationic catalyst species can beused for this purpose. Suitable activators are described in U.S. Pat.Nos. 5,153,157;5,198,401 and 5,241,025, all of which are incorporatedherein by reference, and include trialkyl and triaryl (substituted andunsubstituted) boranes, e.g., tripentafluorophenyl borane, and, moretypically, ionic compounds, such as organoborates. Highly usefulorganoborate ionizing agents include N,N-dimethylaniliniumtetra(pentafluorophenyl)borate and trityl tetrakis(pentafluorophenyl)borate which are particularly useful for the preferred catalysts of theinvention.

Polymeric materials used as supports for the catalysts of the inventionare homopolymers of ethylene and copolymers of ethylene and C₃₋₈α-olefins, collectively referred to herein as polyethylenes. When acopolymer is employed, it will most generally be a copolymer of ethylenewith propylene, butene-1, hexene-1 or octene-1.

The polyethylene supports can have melt indexes ranging from about 0.1up to about 400 g/10 min. or above. However, in a preferred embodimentwhere the supports are microfine polyethylene powders comprised ofparticles which are spheroidal or substantially spheroidal, the meltindex is in the range of from about 1 up to about 125, and, morepreferably, from about 1 up to about 60. All melt indexes referred toherein are determined at 190° C. in accordance with ASTM D 1238,condition E, and are expressed in grams per 10 minutes (g/10 min).

The polymeric supports of the present invention are particulate productscomprised of discrete particles wherein the particles have a median sizefrom 0.5 up to about 1000 microns, and more preferably, from about 5 toabout 500 microns. The polymeric powders can be obtained by spray dryingor by precipitating from solution by the addition of suitableprecipitating agents, e.g., methanol. The supports may also be producedby grinding or milling the polyethylene to produce powders within theacceptable size range. Mechanical grinding may be carried out underambient conditions if the polymer has a sufficiently high melting pointand does not degrade under the grinding conditions; however, it is morecustomary to cryogenically grind. Dry polymeric powders can be sieved torecover particles of the desired size and particle size distribution.Wet grinding techniques wherein the polyethylene is co-milled with aninert liquid, such as heptane, at ambient temperature or below can alsobe used. Suspensions of polymer particles in organic liquid mediumsproduced in this way may be directly used in subsequent catalystpreparation steps. A combination of these procedures can be used

In a particularly useful embodiment of the invention, the particulatepolyethylene supports are “microfine” powders obtained by dispersionprocesses. Spheroidal or substantially spheroidal supports can beproduced in this manner and, in some instances, have been advantageouslyutilized to control polymer morphology. Microfine powders produced usingdispersion processes can also have substantially narrower particle sizedistributions than powders produced by precipitation, grinding ormilling.

Preferred polyethylene supports for the catalysts of the invention arecomprised of discrete spheroidal or substantially spheroidal particlesof median particle size from about 5 microns to about 300 microns.Particle sizes referred to herein are median diameters obtained from theparticle volume distribution curves. Polyethylene powders of this typeare conveniently produced using the dispersion techniques described inU.S. Pat. Nos. 3,422,049, 3,432,483 and 3,746,681, details of which areincorporated herein by reference. In these powder-forming dispersionprocesses, the polyethylene is charged to the reactor with a polarliquid medium and nonionic surfactant and a dispersion is formed inaccordance with conventional dispersing procedures described in the art.

The dispersing apparatus may be any device capable of deliveringsufficient shearing action to the mixture at elevated temperature andpressure. Conventional propeller stirrers designed to impart high shearcan be used for this purpose. The vessel may also be equipped withbaffles to assist in dispersing the copolymer. Particle size andparticle size distribution will vary depending on the shearing actionwhich, in turn, is related to the stirrer design and rate of stirring.Agitation rates can vary over wide limits.

The dispersion process is typically carried out in a vessel whichenables the powder-forming process to be conducted at elevatedtemperature and pressure. In the usual batch process, all of theingredients are charged to the vessel and the mixture is heated to atemperature above the melt point of the copolymer. While the temperaturewill vary depending on the specific polymer being used, it willtypically range from about 175° C. to about 250° C. Since the fluidityof the dispersion is temperature dependent, it may be useful to carryout the process at temperatures substantially above the melting point ofthe polymeric blend to facilitate formation of the dispersion; however,the temperature should not exceed the thermal degradation temperature ofthe polymer.

Stirring is commenced after the desired temperature is reached andcontinued until a dispersion of the desired droplet size is produced.This will vary depending on the particular ethylene homopolymer orcopolymer being used, temperature, amount and type of surfactant, andother process variables.

A polar liquid medium which is not a solvent for the polyethylene isemployed as the dispersant for the formation of these microfine powdersupports. These polar media are hydroxylic compounds and can includewater, alcohols, polyols and mixtures thereof. It is particularlyadvantageous to use water as the dispersing medium or a liquid mediumwhere water is the major component.

The pressure of the process is not critical so long as a liquid phase ismaintained. In general, the pressure can range from about 1 up to about250 atmospheres. The process can be conducted at autogenous pressure orthe pressure can be adjusted to exceed the vapor pressure of the liquidmedium at the operating temperature.

To form acceptable dispersions, one or more dispersing agents arenecessarily employed. Useful dispersing agents are nonionic surfactantswhich are block copolymers of ethylene oxide and propylene oxide.Preferably, these nonionic surfactants are water-soluble blockcopolymers of ethylene oxide and propylene oxide and have molecularweights greater than about 3500. Most will contain a major portion byweight of ethylene oxide and are obtained by polymerizing ethylene oxideonto preformed polyoxypropylene segments. The amount of nonionicsurfactant employed can range from about 4 to about 50 percent, based onthe weight of the copolymer.

Useful nonionic surface active agents of the above type are manufacturedand sold by BASF Corporation, Chemicals Division under the trademarkPluronic. These products are obtained by polymerizing ethylene oxideonto the ends of a preformed polyoxypropylic base. A wide variety ofproducts of this type wherein the molecular weight of thepolyoxypropylene base and the polyoxyethylene segments is varied areavailable. It is also possible to employ products sold under thetrademark Tetronic which are prepared by building propylene oxide blockcopolymer chains onto an ethylenediamine nucleus and then polymerizingwith ethylene oxide.

Powder-forming dispersion processes may also be conducted in acontinuous manner. If continuous operation is employed, the ingredientsare continuously introduced to the system while removing the dispersionfrom another part of the system. The ingredients may be separatelycharged or may be combined for introduction to the autoclave.

Contact of the transition metal complex and boron activator with theparticulate polyethylene support is generally carried out by dissolvingor slurrying the transition metal compound and boron activator compoundin a hydrocarbon and contacting with the support material. Separatehydrocarbon solutions/slurries may be used or both components may beincluded in the same solution/slurry. Conventional inert aliphatic andaromatic hydrocarbons can be employed for this purpose. These includehydrocarbons such as isobutane, pentane, hexane, heptane, toluene andthe like. Mixtures of hydrocarbons may also be employed.

After contacting the solution or slurries of the transition metalcomplex and boron activator with the support for some contact period,the hydrocarbon is usually removed under vacuum or by other known means.The supported catalyst may be washed prior to use and, if desired,resuspended in fresh hydrocarbon. The supported heterometallocenecatalysts may be introduced to the polymerization system either in dryform or in a hydrocarbon medium as a slurry or suspension. Catalystsprepared in this manner exhibit good shelf-life stability and may bestored for extended periods in a dry box or the like without significantdecrease in activity.

The amount of transition metal complex and boron activator compound usedis adjusted so that the molar ratio of boron to transition metal rangesfrom about 0.1:1 to 10:1 and, more preferably, from 1:1 to 3:1.Supported heterometallocene catalysts exhibiting high activity withlittle or no propensity for reactor fouling or sheeting are obtainedusing substantially equimolar amounts, based on the metals, of thetransition metal complex and ionizing agent up to 1.5:1 (B:transitionmetal). The catalysts will generally have from 0.001 to 0.5 mmoletransition metal per gram of support. More commonly, the support willhave from 0.01 to 0.25 mmole transition metal per gram depositedthereon.

While it is not necessary, the polyethylene supports can be pretreatedprior to deposition of the transition metal complex and boron activatorcompound. Such pretreatment can be thermal or chemical in nature or acombination of such treatments can be used. It may also include one ormore wash steps to remove water, surfactants or other impurities. Anythermal pretreatment must necessarily be at moderate temperatures so asnot to cause thermal degradation of the polymeric support. Also, theheating must be below the softening point of the polymer so that thepolymer particles do not become sticky and fuse together.

Chemically pretreating the support prior to deposition of the transitionmetal complex and boron activator may be accomplished in either theliquid or vapor phase. In the liquid phase, the chemical-treating agentis applied to the support as a liquid, either by itself or, morepreferably, as a solution in a suitable hydrocarbon solvent such as ahexane. In the vapor phase, the modifier is contacted with the supportin the form of a gas. Suitable compounds for pretreating the polyolefinsupport can include alumoxanes, alkyl aluminums, alkyl aluminum halides,alkyl aluminum hydrides, alkylsilyl halides, alkyldisilazanes, alkyl andaryl alkoxysilanes, and alkyl, aryl, and alkoxy boron compounds.Specific compounds of the above types include: (poly)methylalumoxane(MAO), trimethylaluminum, triethylaluminum, tripropylaluminum,triisobutylaluminum, diethylaluminum chloride, diisobutylaluminumhydride, ethylaluminum dichloride, trimethylchlorosilane,dimethyldichlorosilane, hexamethyldisilazane, cyclohexylmethyldimethoxysi lane, methyltri methoxysi lane, trimethylboron, triethylboron,tripropylboron, triisobutylboron, trimethoxyboron, triethoxyboron,triphenoxyboron and the like.

The supported heterometallocene catalysts of the invention are usefulfor the polymerization of α-olefins in accordance with knownpolymerization procedures. Most commonly they are employed inconjunction with a co-catalyst, most typically, an organometalliccompound of a Group 2 or 3 metal containing at least one alkyl grouphaving from 1 to 8 carbon atoms. Organometallic alkylating agents whichcan be used as co-catalysts include dialkyl zincs, dialkyl magnesiums,alkyl magnesium halides, alkyl aluminum dihalides, dialkyl aluminumhalides, trialkyl aluminums and alkylalumoxanes. Preferably, aluminumalkyls are employed which can include compounds such as MAO,trimethylaluminum, triethylaluminum, tripropylaluminum,triisopropylaluminum, tributylaluminum, triisobutylaluminum,tripentylaluminum, trihexylaluminum, triheptylaluminum,trioctylaluminum, diethylaluminum hydride, diisopropylaluminum hydride,diisobutylaluminum hydride, diethylaluminum chloride, dipropylaluminumchloride, diisopropylaluminum chloride, diisobutylaluminum chloride,diethylaluminum ethoxide, diisopropylaluminum isopropoxide,ethylaluminum sesquichloride, isopropylaluminum sesquichloride,isobutylaluminum sesquichloride, ethylaluminum dichloride,isopropylaluminum dichloride, isobutylaluminum dichloride andethylaluminum diisopropoxide. Aluminum trialkyls are especially usefulparticularly if the alkyl groups contain from 1 to 4 carbon atoms.

The catalysts of the invention are advantageously used for thepreparation of any of the commonly known polyolefin resins using variedpolymerization procedures and monomers. They are suitable for use inbatch, continuous or semi-continuous operations using single or multiplereactors for homopolymerizing and copolymerizing C₂₋₁₂ olefins. Mostcommonly, they are used to polymerize C₂₋₈ α-olefins in the liquid orgas phases at pressures from 15 psi to 45,000 psi and temperatures from50° C. up to about 300° C. Preferred monomers for such polymerizationsare ethylene, propylene, butene-1, hexene-1, octene-1 and mixturesthereof.

The following examples illustrate the practice of the invention and arerepresentative of various embodiments described and claimed herein. Theyare not intended as a limitation on the scope of the invention andvariations/modification will be apparent to those skilled in the art.

For the examples, all materials used were thoroughly dried prior to useand the customary precautions taken to exclude air and moisture duringcatalyst preparation and polymerization. Polymer densities weredetermined according to ASTM D-1505. The melt index (MI) of the polymerswas measured according to ASTM D-1238, Condition E, using a 2.16 kgweight. Catalyst activity is the number of grams of polymer produced pergram of transition metal per hour.

EXAMPLE 1

A polyethylene supported heterometallocene catalyst of the invention wasprepared as follows: A flask was charged with 1.12 g of small particlesize polyethylene powder (MICROTHENE FN 510 polyolefin powder; meltindex 5; density 0.923; median particle size 20 microns), 0.032 gcyclopentadienyl(1-methylboratabenzene)zirconium dichloride (0.10 mmol),0.122 g trityl tetrakis(pentafluorophenyl)borate (0.13 mol) and toluene(10 ml). The mixture was stirred for one hour and the resulting slurrydried under vacuum to remove the solvent and recover the supportedcatalyst.

The supported heterometallocene catalyst was used to polymerizeethylene. The polymerization was performed in a two-liter, stainlesssteel autoclave. Hydrogen (4 mmoles) was introduced into the reactorfrom a 50-ml vessel. The amount added was determined by measuring thepressure drop in the vessel. Triethylaluminum (0.75 mmoles; 0.3 ml of1.5 M solution in heptane) was then added to the reactor with isobutane(about 800 ml) and the temperature allowed to equilibrate to 75° C.Ethylene was next added to the reactor (to 400 psig) followed by theaddition of a mixture of the supported heterometallocene catalyst (0.021g) and 0.2 ml of the triethylaluminum solution. The polymerization wasconducted for approximately one hour while maintaining the temperatureat 75° C. Ethylene was fed throughout the polymerization to maintain thereactor pressure. At the conclusion of the polymerization run, theautoclave was vented and the solid polymer recovered. 124.3 Grams of aZMI polyethylene were recovered. The calculated catalyst activity was11833 g/gZr/hr. There was no evidence of reactor fouling, i.e., nopolymer was adhered to the walls of the autoclave or the agitator shaftor blades.

COMPARATIVE EXAMPLE A

To demonstrate the superior results obtained with polymer supportedheterometallocene catalysts of the invention, an identically supportedcatalyst was prepared using a well-known metallocene catalyst,biscylopentadienylzirconium dichloride. The comparative catalyst wasprepared by charging 1.15 g of the particulate LDPE support of Example1, 0.033 g biscyclopentadienylzirconium dichloride (0.13 mmol) and 0.115g trityl tetrakis(pentafluorophenyl)borate (0.13 mmol) to the flask. Aslurry of the solids was prepared in toluene (10 ml). The mixture wasstirred for one hour and the polyethylene supported metallocene catalystrecovered by removing the solvent under vacuum.

Following the polymerization procedure described in Example 1, thecomparative catalyst prepared above was evaluated for its ability topolymerize ethylene. Only 15.2 grams polyethylene were produced with thepolymer supported metallocene catalyst. The activity was only 586g/gZr/hr.

COMPARATIVE EXAMPLE B

Another attempt was made to use a polymer supported metallocenecatalyst, however, in this case an alumoxane modifier was substitutedfor the boron activator compound. Alumoxanes are well-known and widelyused modifiers for metallocene catalysts. The supported catalyst wasprepared by charging 1.35 g of the particulate LDPE of Example 1 and0.034 g biscyclopentadienylzirconium dichloride (0.13 mmol/g SiO₂) to aflask with toluene (10 ml). The mixture was stirred and 5 mlpolymethylalumoxane (7 weight percent A1) was added to the slurry.Stirring was continued for one hour and the supported catalyst recoveredin the usual manner. This catalyst had no activity when evaluated usingthe polymerization procedure of Example 1. No polymer was formed afterone hour in the polymerizer.

EXAMPLE 2

To demonstrate the versatility of the polymer supportedheterometallocene catalyst, the catalyst of Example 1 was used tocopolymerize ethylene and butene-1. The copolymerization was conductedinsthe same manner as describe in Example 1 except that no hydrogen wasused and 10 mol butene-1 was included in the polymerizer with theethylene. Catalyst activity was 6914 g/gZr/hr and no reactor fouling wasobserved.

We claim:
 1. A process which comprises polymerizing an olefin in thepresence of a supported catalyst, said catalyst comprising: (a) aparticulate ethylene homopolymer or ethylene-C₃₋₈ α-olefin copolymersupport; (b) a transition metal coordination complex containing at leastone six-membered boraaryl ligand; and (c) a boron activator compound. 2.A process which comprises polymerizing an olefin in the presence of asupported catalyst, said catalyst comprising: (a) a particulate ethylenehomopolymer or ethylene-C₃₋₈ α-olefin copolymer support having a medianparticle size of 0.5 to 1000 microns and a melt index, measuredaccording to ASTM D-1238, Condition E, using a 2.16 kg weight, of from0.1 to 400 g/10 min; (b) a transition metal coordination complex havingthe formula (L*)_(n)(L)_(m)M(X)_(y) in which M is a Group 3-10 metal, L*is six-membered boraaryl, L is a carbocyclic or constrain-inducingligand or L*, X is hydrogen, halogen, hydrocarbyl, alkoxy, siloxy, ordialkylamido, n is 1 or 2, m is 0 to 3, y is 1 to 4, and n+m+y is equalto the valence of M; and (c) a boron activator compound selected fromthe group consisting of tri(pentafluorophenyl)borane,N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate, and trityltetrakis(pentafluorophenyl)borate; wherein the supported catalystcontains from 0.001 to 0.5 mmoles of transition metal per gram ofsupport; and wherein the molar ratio of boron to transition metal is0.1:1 to 10:1.
 3. The process of claim 2 wherein the olefin is ethyleneor a mixture of ethylene and a C₃₋₈ α-olefin.
 4. The process of claim 3conducted in the liquid base with a co-catalyst which is anorganometallic compound of a Group 2 or 3 metal having at least nonealkyl group containing from 1 to 8 carbon atoms.
 5. The process of claim3 conducted in the gas phase with a co-catalyst which is anorganometallic compound of a Group 2 or 3 metal having at least onealkyl group containing from 1 to 8 carbon atoms.